Socioeconomic status (SES) is negatively associated with children's health; however, mediators for this association are not well understood. In this pilot study, we lay the foundation for testing one potential psychological pathway, a cognitive bias toward interpreting ambiguous situations as threatening, and its relationship with cardiovascular reactivity, a risk factor for later cardiovascular disease. Children from lower SES backgrounds have been found to display elevated cardiovascular reactivity to laboratory stressors. It may be that these children, because of their more frequent exposure to danger and stress, develop a bias toward interpreting a wide range of situations, including ambiguous ones as threatening. These children may then display heightened physiological reactivity during such situations. This type of cognitive bias (interpreting ambiguous situations as threatening) may serve as a mediator explaining why lower SES children display heightened cardiovascular reactivity. Ecologically valid measures of cognitive bias that are relevant to children of various SES backgrounds have not been developed, and thus the first goal of this study is to develop and test professionally produced videos of ambiguous and negative social situations. The second goal of this pilot study is to investigate children's cardiovascular responses to these videos. We hypothesize that lower SES will be associated with greater threat perception during ambiguous, but not negative, scenarios and that the relationship between SES and cardiovascular reactivity will be mediated by threat perception during ambiguous scenarios. Finally, we expect that stressful life events will moderate the above relationships. That is, only low SES children who may experience many or at least one severe negative life event will develop such a bias. To test these hypotheses, we will first develop and test the feasibility of four videos of ambiguous and negative scenarios using a sample of 40 Caucasian and African American college freshmen. We then will test cardiovascular reactivity to these videos in a laboratory protocol using a sample of 20 Caucasian and African American adolescents. Adolescents will also be interviewed about their perceptions of these scenarios, and will be asked about stressful life events. Through this study, we seek to establish a methodology for investigating the role of psychological processes in SES and health relationships.